[PATCH] xen: set vma flag VM_PFNMAP in the privcmd mmap file_op

From: Stefano Stabellini
Date: Thu Nov 11 2010 - 10:57:38 EST


Hi all,
this patch fixes the dom0 kernel crash when creating a VM.
Now I am able to create VMs successfully on 2.6.37 rc1, even though
without disk or network access.

---

xen: set vma flag VM_PFNMAP in the privcmd mmap file_op

Set VM_PFNMAP in the privcmd mmap file_op, rather than later in
xen_remap_domain_mfn_range when it is too late because
vma_wants_writenotify has already been called and vm_page_prot has
already been modified.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index c237b81..2be1f36 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -2627,7 +2627,7 @@ int xen_remap_domain_mfn_range(struct vm_area_struct *vma,

prot = __pgprot(pgprot_val(prot) | _PAGE_IOMAP);

- vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
+ BUG_ON(!(vma->vm_flags & (VM_PFNMAP | VM_RESERVED | VM_IO)));

rmd.mfn = mfn;
rmd.prot = prot;
diff --git a/drivers/xen/xenfs/privcmd.c b/drivers/xen/xenfs/privcmd.c
index f80be7f..9aab216 100644
--- a/drivers/xen/xenfs/privcmd.c
+++ b/drivers/xen/xenfs/privcmd.c
@@ -385,7 +385,7 @@ static int privcmd_mmap(struct file *file, struct vm_area_struct *vma)
return -ENOSYS;

/* DONTCOPY is essential for Xen as copy_page_range is broken. */
- vma->vm_flags |= VM_RESERVED | VM_IO | VM_DONTCOPY;
+ vma->vm_flags |= VM_RESERVED | VM_IO | VM_DONTCOPY | VM_PFNMAP;
vma->vm_ops = &privcmd_vm_ops;
vma->vm_private_data = NULL;

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